Already being blamed on al Qaeda and 'foreign nationals', an explosion to take blame way from coalition's agenda for the mess in Iraq, and place it back on the war on terror. This obviousness of this would be laughable if not so tragic

Aftermath of the explosion at the UN headquarters in Baghdad. Photograph: AP

A powerful truck bomb ripped apart the United Nations headquarters in Baghdad today, killing at least 15 people including the UN's top official in Iraq. A senior UN official confirmed that Sergio Vieira de Mello, the UN secretary general's special representative to Iraq, had died after being trapped beneath the rubble of the UN building. Mr de Mello's office appeared to have been the target of the bombing.

Hundreds of UN staff work at the compound, a former hotel in eastern Baghdad. A UN worker in Baghdad told the Associated Press that he had counted 15 white body bags taken from the collapsed building. At least 40 people were injured.

"The explosion was caused by a massive truck bomb. We have evidence to suggest it could have been a suicide attack," Bernard Kerik, the top US law enforcement official in Baghdad, told reporters.

Uday Ahad, an Iraqi security guard at the building said: "I was standing at the gate when it exploded. Many Iraqis and foreigners were wounded." He told Reuters he had pulled three bodies from the rubble.

"Suddenly there was an explosion and everything fell down. There are lots of people inside because no one had gone home yet," said Fouad Victor, a UN employee.

An Associated Press reporter at the scene said he could see about 40 injured people receiving first aid in the front garden. At the nearby al-Kindi Hospital, Dr Munas Amer said at least two people, both Iraqis, were killed in the blast and at least 25 other people had been brought for treatment.

The explosion, which took place at 4.30pm local time (1330 BST) came just days after a truck bomb blew up outside the Jordanian embassy in Baghdad, killing 17 people.

The UN secretary general, Kofi Annan, said he was shocked by the bombing and hoped those responsible for the attack would quickly be brought to justice.

"All of us at the United Nations are shocked and dismayed by today's attack, in which dozens of our colleagues have been injured and an unknown number have lost their lives," Mr Annan said in a statement.

The US president, George Bush, immediately vowed to offer full assistance to the UN and said the "civilised world will not be intimidated".

"The terrororists who struck today have again showed their contempt for the innocent," Mr Bush said. "The terrorists want to return to the days of torture chambers and mass graves. The Iraqi people must reject them and fight terror."

Iraq, he said, is on "an irreversible course to self-government and peace". He said both the US and the UN would continue to stand with the Iraqi people.

US Black Hawk helicopters could be seen flying toward the scene immediately after the explosion, as a column of black smoke filled the sky.

Residents up to one mile away from the blast said that their windows had been blown out by the force of the blast. "My house shook like it did during the bombing at the start of the war," a resident in the area around the hotel said.

Several of the dead and wounded were still trapped under the rubble hours after the explosion, US army captain James Jensen told Reuters.

UN weapons inspectors worked from the hotel during the period before the war as the international community sought, but failed to find, Saddam Hussein's alleged weapons of mass destruction.

"Such a despicable act directed at people whose only aim is to assist the people of Iraq recover from war and years of oppression is to be condemned by the whole international community," the acting UN high commissioner for human rights, Bertrand Ramcharan, said in a statement.

"Such terrorist incidents cannot break the will of the international community to further intensify its efforts to help the people of Iraq," the president of the UN security council, Fayssal Mekdad, told a press conference in New York. He said such attacks would not stop the international body from operating in Iraq and that the council was united against the perpetrators of such assaults and resolved to track them down.

Britain's foreign secretary, Jack Straw, condemned the bombing as an "outrage" and insisted that British and US efforts to rebuild the country would not be deterred.

"I am appalled by this callous attack on the UN headquarters in Baghdad. My thoughts are with the relatives and friends of those who have been killed and injured. I condemn this outrage against the United Nations, its staff and the people of Iraq.

"The victims, including Sergio Vieira de Mello, are people who are dedicating themselves to helping Iraq and the Iraqi people towards a better future."

Aftermath of the explosion at the UN headquarters in Baghdad. Photograph: AP

A powerful truck bomb ripped apart the United Nations headquarters in Baghdad today, killing at least 15 people including the UN's top official in Iraq. A senior UN official confirmed that Sergio Vieira de Mello, the UN secretary general's special representative to Iraq, had died after being trapped beneath the rubble of the UN building. Mr de Mello's office appeared to have been the target of the bombing.

Hundreds of UN staff work at the compound, a former hotel in eastern Baghdad. A UN worker in Baghdad told the Associated Press that he had counted 15 white body bags taken from the collapsed building. At least 40 people were injured.

"The explosion was caused by a massive truck bomb. We have evidence to suggest it could have been a suicide attack," Bernard Kerik, the top US law enforcement official in Baghdad, told reporters.

Uday Ahad, an Iraqi security guard at the building said: "I was standing at the gate when it exploded. Many Iraqis and foreigners were wounded." He told Reuters he had pulled three bodies from the rubble.

"Suddenly there was an explosion and everything fell down. There are lots of people inside because no one had gone home yet," said Fouad Victor, a UN employee.

An Associated Press reporter at the scene said he could see about 40 injured people receiving first aid in the front garden. At the nearby al-Kindi Hospital, Dr Munas Amer said at least two people, both Iraqis, were killed in the blast and at least 25 other people had been brought for treatment.

The explosion, which took place at 4.30pm local time (1330 BST) came just days after a truck bomb blew up outside the Jordanian embassy in Baghdad, killing 17 people.

The UN secretary general, Kofi Annan, said he was shocked by the bombing and hoped those responsible for the attack would quickly be brought to justice.

"All of us at the United Nations are shocked and dismayed by today's attack, in which dozens of our colleagues have been injured and an unknown number have lost their lives," Mr Annan said in a statement.

The US president, George Bush, immediately vowed to offer full assistance to the UN and said the "civilised world will not be intimidated".

"The terrororists who struck today have again showed their contempt for the innocent," Mr Bush said. "The terrorists want to return to the days of torture chambers and mass graves. The Iraqi people must reject them and fight terror."

Iraq, he said, is on "an irreversible course to self-government and peace". He said both the US and the UN would continue to stand with the Iraqi people.

US Black Hawk helicopters could be seen flying toward the scene immediately after the explosion, as a column of black smoke filled the sky.

Residents up to one mile away from the blast said that their windows had been blown out by the force of the blast. "My house shook like it did during the bombing at the start of the war," a resident in the area around the hotel said.

Several of the dead and wounded were still trapped under the rubble hours after the explosion, US army captain James Jensen told Reuters.

UN weapons inspectors worked from the hotel during the period before the war as the international community sought, but failed to find, Saddam Hussein's alleged weapons of mass destruction.

"Such a despicable act directed at people whose only aim is to assist the people of Iraq recover from war and years of oppression is to be condemned by the whole international community," the acting UN high commissioner for human rights, Bertrand Ramcharan, said in a statement.

"Such terrorist incidents cannot break the will of the international community to further intensify its efforts to help the people of Iraq," the president of the UN security council, Fayssal Mekdad, told a press conference in New York. He said such attacks would not stop the international body from operating in Iraq and that the council was united against the perpetrators of such assaults and resolved to track them down.

Britain's foreign secretary, Jack Straw, condemned the bombing as an "outrage" and insisted that British and US efforts to rebuild the country would not be deterred.

"I am appalled by this callous attack on the UN headquarters in Baghdad. My thoughts are with the relatives and friends of those who have been killed and injured. I condemn this outrage against the United Nations, its staff and the people of Iraq.

"The victims, including Sergio Vieira de Mello, are people who are dedicating themselves to helping Iraq and the Iraqi people towards a better future."